CN110797520B - Negative electrode material, and electrochemical device and electronic device comprising same - Google Patents

Negative electrode material, and electrochemical device and electronic device comprising same Download PDF

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CN110797520B
CN110797520B CN201911115652.9A CN201911115652A CN110797520B CN 110797520 B CN110797520 B CN 110797520B CN 201911115652 A CN201911115652 A CN 201911115652A CN 110797520 B CN110797520 B CN 110797520B
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anode material
carbon
layer
silicon
polymer layer
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CN110797520A (en
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陈志焕
姜道义
崔航
谢远森
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Ningde Amperex Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

The present application relates to an anode material, and an electrochemical device and an electronic device including the same. An anode material includes silicon-containing particles including a silicon composite matrix and a polymer layer coating at least a portion of the silicon composite matrix, and the polymer layer includes a carbon material. The cathode material has good cycle performance, and meanwhile, a battery prepared from the cathode material has good rate performance and low expansion rate.

Description

Negative electrode material, and electrochemical device and electronic device comprising same
Technical Field
The application relates to the field of energy storage, in particular to a negative electrode material, an electrochemical device and an electronic device comprising the same, and particularly relates to a lithium ion battery.
Background
With the popularization of consumer electronics products such as notebook computers, mobile phones, tablet computers, mobile power sources, unmanned aerial vehicles and the like, the requirements on electrochemical devices therein are becoming stricter. For example, batteries are required not only to be lightweight but also to have high capacity and long operating life. Lithium ion batteries have already occupied a mainstream status in the market by virtue of their outstanding advantages of high energy density, high safety, no memory effect, long operating life, and the like.
Disclosure of Invention
Embodiments of the present application provide an anode material and a method of preparing the anode material in an attempt to solve at least one of the problems existing in the related art to at least some extent. The embodiment of the application also provides a negative electrode, an electrochemical device and an electronic device using the negative electrode material.
In one embodiment, the present application provides an anode material comprising silicon-containing particles comprising a silicon composite matrix and a polymer layer coating at least a portion of the silicon composite matrix, and the polymer layer comprising a carbon material.
In another embodiment, the present application provides a method of preparing an anode material, the method comprising:
mixing SiOxDispersing the powder, the carbon material and the polymer in a solvent at a high speed for about 1-20h to obtain a suspension; and
the solvent in the suspension is removed and,
wherein
About 0.5< x < about 1.5.
In another embodiment, the present application provides an anode comprising an anode material according to embodiments of the present application.
In another embodiment, the present application provides an electrochemical device comprising an anode according to embodiments of the present application.
In another embodiment, the present application provides an electronic device comprising an electrochemical device according to an embodiment of the present application.
The cathode active material has good cycle performance, and a lithium ion battery prepared from the cathode active material has good rate performance and low expansion rate.
Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the present application.
Drawings
Drawings necessary for describing embodiments of the present application or the prior art will be briefly described below in order to describe the embodiments of the present application. It is to be understood that the drawings in the following description are only some of the embodiments of the present application. It will be apparent to those skilled in the art that other embodiments of the drawings can be obtained from the structures illustrated in these drawings without the need for inventive work.
Fig. 1 shows a schematic view of the structure of an anode active material according to an embodiment of the present application.
Fig. 2 shows a schematic view of the structure of an anode active material according to another embodiment of the present application.
Fig. 3 shows an X-ray diffraction (XRD) pattern of the negative active material of example 12 of the present application.
Fig. 4 shows an X-ray diffraction (XRD) pattern of the negative active material of comparative example 4 of the present application.
Fig. 5 shows a volume-based particle size distribution curve of the negative electrode active material of example 16 of the present application.
Fig. 6 shows a volume-based particle size distribution curve of the negative active material of comparative example 6 of the present application.
Fig. 7 shows a Scanning Electron Microscope (SEM) picture of the negative active material of example 16 of the present application.
Fig. 8 shows a Scanning Electron Microscope (SEM) picture of the negative active material of comparative example 6 of the present application.
Detailed Description
Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.
As used in this application, the term "about" is used to describe and illustrate minor variations. When used in conjunction with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely as well as instances where the event or circumstance occurs in close proximity. For example, when used in conjunction with numerical values, the term can refer to a range of variation that is less than or equal to ± 10% of the stated numerical value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%.
In the present application, Dv50 is the particle diameter corresponding to 50% of the cumulative volume percentage of the negative electrode active material, and is expressed in μm.
In the present application, Dn10 is a particle diameter in μm corresponding to the cumulative percentage of the amount of the negative electrode active material of 10%.
In the present application, the silicon compound contains elemental silicon, a silicon compound, a mixture of elemental silicon and a silicon compound, or a mixture of different silicides.
Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the detailed description and claims, a list of items connected by the terms "one of," "one of," or other similar terms may mean any one of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means a alone or B alone. In another example, if items A, B and C are listed, the phrase "one of A, B and C" means only a; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
In the detailed description and claims, a list of items linked by the term "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
First, negative electrode material
Embodiments provide an anode material comprising silicon-containing particles comprising a silicon composite matrix and a polymer layer coating at least a portion of the silicon composite matrix, and the polymer layer comprising a carbon material.
In some embodiments, the silicon composite matrix comprises a silicon-containing species, wherein the silicon-containing species in the silicon composite matrix and one or more of the other species in the anode material other than the silicon-containing species may form a composite. In some embodiments, the silicon composite matrix comprises particles capable of intercalating and deintercalating lithium ions.
In some embodiments, the silicon composite matrix comprises SiOxAnd x is greater than or equal to about 0.6 and less than or equal to about 1.5.
In some embodiments, the silicon composite matrix comprises nano-Si grains, SiO2Or any combination thereof.
In some embodiments, the nano-Si grains are less than about 100nm in size. In some embodiments, the nano-Si grains are less than about 50nm in size. In some embodiments, the nano-Si grains are less than about 20nm in size. In some embodiments, the nano-Si grains are less than about 5nm in size. In some embodiments, the nano-Si grains are less than about 2nm in size.
In some embodiments, the polymer layer comprises polyvinylidene fluoride and derivatives thereof, carboxymethylcellulose and derivatives thereof, sodium carboxymethylcellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, poly (styrene-butadiene rubber), polyacrylamide, polyimide, polyamideimide, or any combination thereof.
In some embodiments, the carbon material in the polymer layer comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
In some embodiments, the weight percentage of the polymer layer is about 0.05 to 15 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.05 to 10 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.05 to 5 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.1-4 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.5-3 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 1 wt%, about 1.5 wt%, or about 2 wt% based on the total weight of the anode material.
In some embodiments, the polymer layer has a thickness of about 1nm to 200 nm. In some embodiments, the polymer layer has a thickness of about 1nm to 100 nm. In some embodiments, the polymer layer has a thickness of about 5nm to 90 nm. In some embodiments, the polymer layer has a thickness of about 10nm to 80 nm. In some embodiments, the polymer layer has a thickness of about 5nm, about 20nm, about 30nm, about 40nm, about 50nm, about 60nm, or about 70 nm.
In some embodiments, the anode material has a maximum intensity value of I in the range of about 27.5 ° to 29.0 ° 2 θ in the X-ray diffraction pattern2The highest intensity value assigned to the range of about 20.5-22.0 is I1Wherein is about 0<I2/I1Less than or equal to about 1.
In some embodiments, the anode material has a 2 θ ascribed to a maximum intensity value of I of about 28.4 ° in an X-ray diffraction pattern2The highest intensity value assigned to the range of about 21.0 is I1Wherein is about 0<I2/I1Less than or equal to about 1. In some embodiments, I2/I10.2, 0.3, 0.4, 0.5 or 0.6.
In some embodiments, D of the silicon-containing particles V50 is in the range of about 2.5 μm to 20 μm, and the silicon-containing particles have a particle size distribution satisfying: about 0.25. ltoreq. Dn10/Dv 50. ltoreq.about 0.6.
In some embodiments, the silicon-containing particles have a particle size distribution satisfying about 0.4. ltoreq. Dn10/Dv 50. ltoreq.0.5. In some embodiments, the particle size distribution of the silicon composite matrix satisfies about Dn10/Dv50 of about 0.3 or about 0.35.
In some embodiments, D of the silicon-containing particles V50 is in the range of about 2.5 μm to 20 μm. In some embodiments, D of the silicon-containing particles V50 is in the range of about 3 μm to 10 μm. In some embodiments, D of the silicon composite substrate V50 is in the range of about 4 μm to 9 μm. In some embodiments, D of the silicon composite substrate V50 is in the range of about 4.5 μm to 6 μm. In some embodimentsD of the silicon composite substrate V50 is in the range of about 2 μm, about 3.5 μm, about 4.5 μm, or about 5 μm.
In some embodiments, the silicon-containing particles further comprise an oxide MeOyLayer of said oxide MeOyA layer between the silicon composite substrate and the polymer layer, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, wherein y is about 0.5-3; and wherein the oxide MeOyThe layer comprises a carbon material.
In some embodiments, the oxide MeOyA layer covers at least a portion of the silicon composite substrate.
In some embodiments, the oxide MeOyIncluding Al2O3、SiO2、TiO2、Mn2O3、MnO2、CrO3、Cr2O3、CrO2、V2O5、VO、CoO、Co2O3、Co3O4、ZrO2Or any combination thereof.
In some embodiments, the oxide MeOyThe carbon material in the layer comprises amorphous carbon, carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof. In some embodiments, the amorphous carbon is a carbon material obtained by sintering a carbon precursor at a high temperature. In some embodiments, the carbon precursor comprises polyvinylpyrrolidone, sodium carboxymethylcellulose, polyvinyl alcohol, polypropylene, acid phenolic resin, polyester resin, polyamide resin, epoxy resin, polyurethane, polyacrylic resin, or any combination thereof.
In some embodiments, the oxide MeOyThe thickness of the layer is about 0.5nm to 1100 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 1nm to 800 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 1nm to 600 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 1nm to 20 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 2nm, about 10nm, about 20nm, about 50nmnm, about 100nm, about 200nm, or about 300 nm.
In some embodiments, the weight percentage of Me element is about 0.001 wt% to 0.9 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.02 wt% to 1 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.02 wt% to 0.8 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.05 wt%, about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, or about 0.8 wt%, based on the total weight of the anode material.
In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.05 wt% and 1 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.1 wt% and 0.9 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.2 wt% and 0.8 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, or about 0.7 wt%.
In some embodiments, the anode material has a specific surface area of about 1-50m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 5-40m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 10-30m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 1m2G, about 5m2In the range of/g or about 10m2/g。
Preparation method of anode material
An embodiment of the present application provides a method for preparing any one of the above-mentioned anode materials, including:
(1) mixing SiOxPowders, carbon materials and polymers in solventsDispersing at medium and high speed for about 1-20h to obtain suspension; and
(2) the solvent in the suspension is removed and,
wherein about 0.5< x < about 1.5.
In some embodiments, the polymer comprises polyvinylidene fluoride and derivatives thereof, carboxymethylcellulose and derivatives thereof, sodium carboxymethylcellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, poly (styrene-butadiene rubber), polyacrylamide, polyimide, polyamideimide, or any combination thereof.
In some embodiments, the carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
In some embodiments, the solvent comprises water, ethanol, methanol, tetrahydrofuran, acetone, chloroform, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, toluene, xylene, or any combination thereof.
In some embodiments, the silicon oxide SiOxCan be commercial silicon oxide and can also be silicon oxide SiO prepared by the method of the inventionxIn which the silicon oxide SiO prepared according to the process of the invention x2 theta in the X-ray diffraction pattern has a maximum intensity value I within a range of about 27.5 DEG to 29.0 DEG2The highest intensity value assigned to the range of about 20.5-22.0 is I1Wherein is about 0<I2/I1Less than or equal to about 1.
Satisfies about 0 in the present invention<I2/I1Silicon oxide SiO ≦ about 1xThe preparation method comprises the following steps:
(1) mixing silicon dioxide and metal silicon powder in a molar ratio of about 1:5-5:1 to obtain a mixed material;
(2) at about 10-4-10-1Heating the mixed material at a temperature in the range of about 1200 ℃ and 1600 ℃ for about 5-30 hours under the kPa pressure range to obtain a gas;
(3) condensing the gas obtained to obtain a solid;
(4) pulverizing and sieving the solids; and
(5) heat-treating said solid in the range of about 400-1800 ℃ for about 0.5-15h, cooling said heat-treated solid to satisfy about 0<I2/I1Silicon oxide SiO ≦ about 1x。
In some embodiments, the silica to metal silicon powder molar ratio is about 1:4 to 4: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1:3 to 3: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1:2 to 2: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1: 1.
In some embodiments, the pressure range is about 10-4-10-1kPa. In some embodiments, the pressure is about 1Pa, about 10Pa, about 20Pa, about 30Pa, about 40Pa, about 50Pa, about 60Pa, about 70Pa, about 80Pa, about 90Pa, or about 100 Pa.
In some embodiments, the heating temperature is about 1200-1500 ℃. In some embodiments, the heating temperature is about 1300 ℃, 1350 ℃, about 1400 ℃, or about 1450 ℃.
In some embodiments, the heating time is about 5-20 hours. In some embodiments, the heating time is about 10-25 hours. In some embodiments, the heating time is about 6 hours, about 8 hours, about 10 hours, about 12 hours, about 14 hours, about 16 hours, or about 18 hours.
In some embodiments, the mixing is performed by a ball mill, a V-blender, a three-dimensional blender, an air blender, or a horizontal blender.
In some embodiments, the heating and heat treating are performed under an inert gas blanket. In some embodiments, the inert gas comprises nitrogen, argon, helium, or a combination thereof.
In some embodiments, the method further comprises the step of heat treating after sieving.
In some embodiments, the heat treatment time is about 400-1500 ℃. In some embodiments, the heat treatment time is about 500-. In some embodiments, the time of the heat treatment is about 600 ℃, about 800 ℃, or about 1000 ℃.
In some embodiments, the heat treatment time is about 1-15 hours. In some embodiments, the heat treatment time is about 2-12 hours. In some embodiments, the time of the heat treatment is about 3 hours, about 5 hours, about 8 hours, about 10 hours, about 12 hours, or about 15 hours.
In some embodiments, the method of preparing the anode material further comprises providing the surface with a silicon compound SiO of a polymer layerxThe granules are subjected to a step of sieving and classification. Sieving and grading to obtain the silicon compound SiO with a polymer layer on the surfacexD of the particles V50 is in the range of about 2.5 μm to 20 μm and has a particle size distribution satisfying: about 0.25. ltoreq. Dn10/Dv 50. ltoreq.about 0.6.
In some embodiments, the method of preparing the anode material may be on silicon oxide SiOxSurface first coated with MeOyCoating with polymer layer, wherein the silicon oxide is SiOxSurface coated MeOyThe steps of the layer include:
(1) silicon oxide SiOxPowder, carbon material and oxide precursor MeTnForming a mixed solution in the presence of an organic solvent and deionized water;
(2) drying the mixed solution to obtain powder; and
(3) sintering the powder at about 250 ℃ and 1000 ℃ for about 0.5-15h to obtain the powder with the oxide MeO on the surfaceySilicon compound SiO of the layerxParticles;
wherein x is from about 0.5 to about 1.5, y is from about 0.5 to about 3,
wherein Me comprises at least one of Al, Si, Ti, Mn, Cr, V, Co or Zr,
wherein T comprises at least one of methoxy, ethoxy, isopropoxy, or halogen, and
wherein n is 1, 2, 3 or 4.
In some embodiments, the oxide precursor MeTnIncluding isopropyl titanate, aluminum isopropoxide, or combinations thereof.
In some embodiments, the carbon precursor comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, polyvinylpyrrolidone, sodium carboxymethylcellulose, polyvinyl alcohol, polypropylene, acid phenolic resins, polyester resins, polyamide resins, epoxy resins, polyurethanes, polyacrylic resins, or any combination thereof.
In some embodiments, the sintering temperature is about 250-. In some embodiments, the sintering temperature is about 400-. In some embodiments, the sintering temperature is about 400-650 ℃. In some embodiments, the sintering temperature is about 300 ℃, about 450 ℃, about 500 ℃, or about 600 ℃.
In some embodiments, the sintering time is about 1-15 hours. In some embodiments, the sintering time is about 1-10 hours. In some embodiments, the sintering time is about 1.5-5 hours. In some embodiments, the sintering time is about 2 hours, about 3 hours, or about 4 hours.
In some embodiments, the organic solvent comprises at least one of: ethanol, methanol, N-hexane, N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol or N-propanol. In some embodiments, the organic solvent is ethanol.
In some embodiments, the halogen comprises F, Cl, Br, or a combination thereof.
In some embodiments, the sintering is performed under an inert gas blanket. In some embodiments, the inert gas comprises nitrogen, argon, or a combination thereof.
In some embodiments, the drying is spray drying, with a drying temperature of about 100-.
Fig. 1 shows a schematic view of the structure of an anode active material according to an embodiment of the present application. Wherein the inner layer 1 is a silicon composite matrix and the outer layer 2 is a polymer layer comprising a carbon material. The polymer layer containing the Carbon Nano Tube (CNT) is coated on the surface of the negative active material, and the CNT can be bound on the surface of the negative active material by using the polymer, so that the interface stability of the CNT on the surface of the negative active material is favorably improved, and the cycle performance of the CNT is improved.
Fig. 2 shows a schematic view of the structure of an anode active material according to another embodiment of the present application. Wherein the inner layer 1 is a silicon composite matrix and the intermediate layer 2 is an oxide MeO comprising a carbon materialyThe outer layer 3 is a polymer layer containing a carbon material. Oxide MeO coating the silicon composite matrixyThe oxide can react with HF in the electrolyte to reduce the content of HF in the electrolyte in the circulating process and reduce the etching of HF on the surface of the silicon material, so that the circulating performance of the material is further improved. Oxide MeOyThe carbon material doped in the layer is beneficial to forming a lithium ion conductor after lithium is embedded in the first charge-discharge process, and is beneficial to realizing the conduction of ions. In addition, the oxide MeOyThe doping of the layer with a certain amount of carbon may enhance the conductivity of the negative active material.
Fig. 3 shows an X-ray diffraction (XRD) pattern of the negative active material of example 12 of the present application. As can be seen from FIG. 3, the anode active material has a maximum intensity value I in the range of about 28.0 to 29.0 in terms of 2 θ in the X-ray diffraction pattern2The highest intensity value is assigned to I in the range of about 20.5 DEG to 21.5 DEG1Wherein is about 0<I2/I1Less than or equal to about 1. I is2/I1The magnitude of the number reflects the degree to which the material is affected by disproportionation. I is2/I1The larger the value, the larger the size of the nano silicon crystal grains inside the negative electrode active material. When I is2/I1When the value is more than 1, the negative electrode active material may cause a sharp increase in stress in a local region during lithium intercalation, thereby causing structural deterioration of the negative electrode active material during cycling. In addition, the ability of the grain boundaries to diffuse during ion diffusion can be affected by the creation of nanocrystalline distributions. The inventor of the present application finds that when I2/I1The value satisfies about 0<I2/I1When the content is less than or equal to about 1, the negative electrode active material has good cycle performance, and the lithium ion battery prepared from the negative electrode active material has good expansion resistance.
Fig. 4 shows an X-ray diffraction (XRD) pattern of the negative active material of comparative example 4 of the present application. As can be seen from FIG. 4, I of the negative active material of comparative example 42/I1The value is clearly greater than 1. Compared with the negative active material of example 12, the negative active material of comparative example 4 has poor cycle performance, and the lithium ion battery prepared therefrom has high expansion rate and rate capabilityAnd (4) poor.
Fig. 5 is a volume-based particle size distribution curve of the negative electrode active material of example 16. It can be seen from fig. 5 that the particle size distribution of the negative active material particles of example 16 is relatively uniform and the distribution is relatively narrow. The lithium ion battery prepared from the negative active material of example 16 exhibited more satisfactory cycle characteristics and anti-swelling properties.
Fig. 6 is a volume-based particle size distribution curve of the negative electrode active material of comparative example 6. It can be seen from fig. 6 that the negative active material of comparative example 6 has a certain number of small particles and thus has poor cycle performance. The presence of small fine particles accelerates the etching of the particles by the electrolyte and thus accelerates deterioration of cycle performance. On the other hand, since the small particles are rapidly etched by the electrolyte, a large amount of by-products are generated on the surface thereof, and thus the anti-swelling property of the lithium ion battery prepared therefrom is inferior to that of the lithium ion battery prepared from the negative active material of example 16.
Fig. 7 and 8 show Scanning Electron Microscope (SEM) pictures of the negative active materials in example 16 and comparative example 6, respectively. The size distribution of the particles can be seen visually in fig. 7 and 8. Fig. 8 shows that a certain number of small particles are present in the anode active material of comparative example 6.
Third, negative pole
The embodiment of the application provides a negative electrode. The negative electrode includes a current collector and a negative active material layer on the current collector. The negative active material layer includes a negative electrode material according to an embodiment of the present application.
In some embodiments, the negative active material layer includes a binder. In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon.
In some embodiments, the negative active material layer includes a conductive material. In some embodiments, the conductive material includes, but is not limited to: natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, or polyphenylene derivative.
In some embodiments, the current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal.
In some embodiments, the negative electrode may be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector.
In some embodiments, the solvent may include, but is not limited to: n-methyl pyrrolidone.
Fourth, positive electrode
Materials, compositions, and methods of making positive electrodes useful in embodiments of the present application include any of the techniques disclosed in the prior art. In some embodiments, the positive electrode is the positive electrode described in U.S. patent application No. US9812739B, which is incorporated by reference herein in its entirety.
In some embodiments, the positive electrode includes a current collector and a positive active material layer on the current collector.
In some embodiments, the positive active material includes, but is not limited to: lithium cobaltate (LiCoO2), lithium Nickel Cobalt Manganese (NCM) ternary materials, lithium iron phosphate (LiFePO4) or lithium manganate (LiMn2O 4).
In some embodiments, the positive active material layer further includes a binder, and optionally a conductive material. The binder improves the binding of the positive electrode active material particles to each other, and also improves the binding of the positive electrode active material to the current collector.
In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or the like.
In some embodiments, the conductive material includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer is a polyphenylene derivative.
In some embodiments, the current collector may include, but is not limited to: aluminum.
The positive electrode may be prepared by a preparation method well known in the art. For example, the positive electrode can be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector. In some embodiments, the solvent may include, but is not limited to: n-methyl pyrrolidone.
Fifth, electrolyte
The electrolyte that may be used in the embodiments of the present application may be an electrolyte known in the art.
In some embodiments, the electrolyte includes an organic solvent, a lithium salt, and an additive. The organic solvent of the electrolyte according to the present application may be any organic solvent known in the art that can be used as a solvent of the electrolyte. The electrolyte used in the electrolyte according to the present application is not limited, and may be any electrolyte known in the art. The additive of the electrolyte according to the present application may be any additive known in the art as an additive of electrolytes.
In some embodiments, the organic solvent includes, but is not limited to: ethylene Carbonate (EC), Propylene Carbonate (PC), diethyl carbonate (DEC), Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
In some embodiments, the lithium salt comprises at least one of an organic lithium salt or an inorganic lithium salt.
In some embodiments, the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF)6) Lithium tetrafluoroborate (LiBF)4) Lithium difluorophosphate (LiPO)2F2) Lithium bis (trifluoromethanesulfonylimide) LiN (CF)3SO2)2(LiTFSI), lithium bis (fluorosulfonyl) imide Li (N (SO)2F)2) (LiFSI), lithium bis (oxalato) borate LiB (C)2O4)2(LiBOB) or lithium difluorooxalato borate LiBF2(C2O4)(LiDFOB)。
In some embodiments, the concentration of lithium salt in the electrolyte is: about 0.5 to 3mol/L, about 0.5 to 2mol/L, or about 0.8 to 1.5 mol/L.
Sixth, the barrier film
In some embodiments, a separator is provided between the positive and negative electrodes to prevent short circuits. The material and shape of the separation film that can be used for the embodiment of the present application are not particularly limited, and may be any of the techniques disclosed in the prior art. In some embodiments, the separator includes a polymer or inorganic substance or the like formed of a material stable to the electrolyte of the present application.
For example, the release film may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be used.
At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.
The inorganic layer comprises inorganic particles and a binder, wherein the inorganic particles are selected from one or more of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is selected from one or a combination of more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
The polymer layer comprises a polymer, and the material of the polymer is selected from at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
Seventh, electrochemical device
Embodiments of the present application provide an electrochemical device including any device in which an electrochemical reaction occurs.
In some embodiments, the electrochemical device of the present application includes a positive electrode having a positive electrode active material capable of occluding and releasing metal ions; a negative electrode according to an embodiment of the present application; an electrolyte; and a separator interposed between the positive electrode and the negative electrode.
In some embodiments, the electrochemical devices of the present application include, but are not limited to: all kinds of primary batteries, secondary batteries, fuel cells, solar cells or capacitors.
In some embodiments, the electrochemical device is a lithium secondary battery.
In some embodiments, the lithium secondary battery includes, but is not limited to: a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
Eight, electronic device
The electronic device of the present application may be any device using the electrochemical device according to the embodiment of the present application.
In some embodiments, the electronic devices include, but are not limited to: a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting apparatus, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized household battery or a lithium ion capacitor, and the like.
Taking a lithium ion battery as an example and describing the preparation of the lithium ion battery with reference to specific examples, those skilled in the art will understand that the preparation method described in the present application is only an example, and any other suitable preparation method is within the scope of the present application.
Examples
The following describes performance evaluation according to examples and comparative examples of lithium ion batteries of the present application.
Method for evaluating performance of negative electrode active material
1. Method for testing powder property of negative electrode active material
(1) And (3) observing the micro-morphology of the powder particles: observing the microscopic morphology of the powder by using a scanning electron microscope to represent the surface coating condition of the material, wherein the selected test instruments are as follows: OxFORD EDS (X-max-20 mm)2) And the accelerating voltage is 15KV, the focal length is adjusted, the observation multiple is observed at high power from 50K, and the particle agglomeration condition is mainly observed at low power of 500-2000.
(2) Specific surface area test: after the adsorption amount of the gas on the solid surface at different relative pressures is measured at constant temperature and low temperature, the adsorption amount of the monolayer of the sample is obtained based on the Bronuore-Eltt-Taylor adsorption theory and the formula (BET formula) thereof, and the specific surface area of the solid is calculated.
About 1.5-3.5g of the powder sample was weighed into a test sample tube of TriStar II 3020, degassed at about 200 ℃ for 120min and tested.
(3) And (3) testing the granularity: about 0.02g of the powder sample was added to a 50ml clean beaker, about 20ml of deionized water was added, a few drops of 1% surfactant were added dropwise to completely disperse the powder in water, sonicated in a 120W ultrasonic cleaner for 5 minutes, and the particle size distribution was measured using a MasterSizer 2000.
(4) And (3) testing the carbon content: the sample is heated and combusted at high temperature by a high-frequency furnace under the condition of oxygen enrichment to respectively oxidize carbon and sulfur into carbon dioxide and sulfur dioxide, the gas enters a corresponding absorption cell after being treated, corresponding infrared radiation is absorbed, and then the infrared radiation is converted into corresponding signals by a detector. The signal is sampled by a computer, is converted into a numerical value in direct proportion to the concentration of carbon dioxide and sulfur dioxide after linear correction, then the value of the whole analysis process is accumulated, after the analysis is finished, the accumulated value is divided by a weight value in the computer, and then multiplied by a correction coefficient, and blank is deducted, thus the percentage content of carbon and sulfur in the sample can be obtained. The sample was tested using a high frequency infrared carbon sulfur analyzer (Shanghai DE Ky HCS-140).
(5) XRD test: weighing 1.0-2.0g of sample, pouring the sample into a groove of a glass sample rack, compacting and grinding the sample by using a glass sheet, testing by using an X-ray diffractometer (Bruk, D8) according to JJS K0131-2And the highest intensity I attributed to 21.0 DEG1Thereby calculating I2/I1The ratio of (a) to (b).
(6) And (3) testing metal elements: weighing a certain amount of sample, adding a certain amount of concentrated nitric acid into the sample, performing microwave digestion to obtain a solution, washing the obtained solution and filter residue for multiple times, fixing the volume to a certain volume, testing the plasma intensity of metal elements in the solution through ICP-OES, and calculating the metal content in the solution according to a standard curve of the measured metal, thereby calculating the amount of the metal elements contained in the material.
The weight percentages of each material in the following tables are calculated based on the total weight of the anode active material.
Second, electrical property test method of negative electrode active material
1. The button cell testing method comprises the following steps:
under a dry argon atmosphere inMixing Propylene Carbonate (PC), Ethylene Carbonate (EC) and diethyl carbonate (DEC) (weight ratio about 1: 1: 1) to obtain a solvent, and adding LiPF6Mixing uniformly, wherein LiPF6Was added with about 7.5 wt% of fluoroethylene carbonate (FEC), and mixed uniformly to obtain an electrolyte solution.
The negative electrode active materials, conductive carbon black, and a binder PAA (modified polyacrylic acid, PAA) obtained in examples and comparative examples were mixed in a weight ratio of about 80: 10: 10 adding the mixture into deionized water, stirring to form slurry, coating by using a scraper to form a coating with the thickness of about 100 mu m, drying at about 85 ℃ for about 12 hours in a vacuum drying oven, cutting into round pieces with the diameter of about 1cm by using a punch in a drying environment, taking a metal lithium piece as a counter electrode in a glove box, selecting a ceglard composite film as an isolating film, and adding electrolyte to assemble the button cell. The charging and discharging tests are carried out on the battery by using a blue electricity (LAND) series battery test, the charging and discharging capacity of the battery is tested, and the first coulombic efficiency of the battery is the ratio of the charging capacity to the discharging capacity.
2. Full battery test
(1) Preparation of lithium ion battery
Preparation of the Positive electrode
Subjecting LiCoO to condensation2The conductive carbon black and polyvinylidene fluoride (PVDF) are fully stirred and uniformly mixed in an N-methyl pyrrolidone solvent system according to the weight ratio of about 95 percent to 2.5 percent to prepare the anode slurry. And coating the prepared anode slurry on an anode current collector aluminum foil, drying and cold pressing to obtain the anode.
Preparation of the negative electrode
Graphite, negative electrode active materials prepared according to examples and comparative examples, and a conductive agent (conductive carbon black, Super)
Figure GDA0002926826100000151
) And binder PAA in a weight ratio of about 70%: 15%: 5%: 10%, adding an appropriate amount of water, and kneading at a solid content of about 55 wt% to 70 wt%. Adding a proper amount of water, and adjusting the viscosity of the slurry to about 4000-6000 Pa.s to prepare the cathode slurry.
And coating the prepared negative electrode slurry on a negative electrode current collector copper foil, drying and cold pressing to obtain a negative electrode.
Preparation of the electrolyte
Under dry argon atmosphere, LiPF is added into a solvent formed by mixing Propylene Carbonate (PC), Ethylene Carbonate (EC) and diethyl carbonate (DEC) (the weight ratio is about 1: 1: 1)6Mixing uniformly, wherein LiPF6The concentration of (A) was about 1.15mol/L, and about 7.5 wt% of fluoroethylene carbonate (FEC) was further added thereto and mixed uniformly to obtain an electrolyte solution.
Preparation of the separator
The PE porous polymer film is used as a separation film.
Preparation of lithium ion battery
The anode, the isolating film and the cathode are sequentially stacked, and the isolating film is positioned between the anode and the cathode to play a role in isolation. And winding to obtain the naked electric core. And arranging the bare cell in an external package, injecting electrolyte and packaging. The lithium ion battery is obtained through the technological processes of formation, degassing, edge cutting and the like.
(2) And (3) testing the cycle performance:
the test temperature was 25/45 ℃, and the test temperature was constant current charged to 4.4V at 0.7C, constant voltage charged to 0.025C, and discharged to 3.0V at 0.5C after standing for 5 minutes. And taking the capacity obtained in the step as the initial capacity, carrying out a cyclic test of 0.7C charging/0.5C discharging, and taking the ratio of the capacity of each step to the initial capacity to obtain a capacity fading curve. The cycle number of the battery with the capacity retention rate of 90% after the cycle at 25 ℃ is recorded as the room-temperature cycle performance of the battery, the cycle number of the battery with the capacity retention rate of 80% after the cycle at 45 ℃ is recorded as the high-temperature cycle performance of the battery, and the cycle performance of the materials is compared by comparing the cycle number of the two cases.
(3) And (3) testing discharge rate:
discharging to 3.0V at 0.2C at 25 ℃, standing for 5min, charging to 4.45V at 0.5C, charging to 0.05C at constant voltage, standing for 5min, adjusting discharge rate, performing discharge tests at 0.2C, 0.5C, 1C, 1.5C and 2.0C respectively to obtain discharge capacity, comparing the capacity obtained at each rate with the capacity obtained at 0.2C, and comparing rate performance by comparing the ratio of 2C to 0.2C.
(4) And (3) testing the full charge expansion rate of the battery:
and (3) testing the thickness of the fresh battery in the half-charging (50% charging State (SOC)) by using a spiral micrometer, circulating to 400 circles, and testing the thickness of the battery at the moment by using the spiral micrometer when the battery is in the full-charging (100% SOC) state, and comparing the thickness of the battery with the thickness of the fresh battery in the initial half-charging (50% SOC) state to obtain the expansion rate of the full-charging (100% SOC) battery at the moment.
Preparation of negative active material
1. Preparation of negative active Material having Polymer layer on surface
Negative active materials in examples 1 to 10 and comparative examples 1 and 2 were prepared by the following methods:
(1) dispersing a carbon material (single-walled carbon nanotubes (SCNT) and/or multi-walled carbon nanotubes (MCNT)) and a polymer in water at a high speed for about 12 hours to obtain a uniformly mixed slurry;
(2) commercial silicon oxide SiOx(0.5<x<1.5，DV50-5 μm) was added to the slurry uniformly mixed in (1) and stirred for about 4 hours to obtain a uniformly mixed dispersion; and
(3) the dispersion was spray dried (inlet temperature about 200 ℃ C., outlet temperature about 110 ℃ C.) to give a powder.
Table 1-1 shows the compositions of the anode active materials of examples 1-10 and comparative examples 1 and 2.
TABLE 1-1
Figure GDA0002926826100000171
Wherein "-" means that the substance was not added.
The English abbreviations in Table 1-1 are all as follows:
SCNT: single-walled carbon nanotubes
MCNT: multiwalled carbon nanotube
CMC-Na: sodium carboxymethylcellulose
PVP: polyvinylpyrrolidone
PVDF: polyvinylidene fluoride
PAANa: polyacrylamide sodium salt
Tables 1-2 show the results obtained from examples 1-10 and comparative examples 1 and 2 and comparative example 3 (commercial silicon oxide SiO described above)x) The performance test results of the lithium ion battery prepared from the negative active material.
Tables 1 to 2
Figure GDA0002926826100000172
Figure GDA0002926826100000181
As can be seen from the test results of examples 1 to 10 and comparative examples 1 to 3, SiO was observed for silicon oxidexThe polymer layer containing the carbon nano tube is coated, so that the cycle performance and the rate capability of the lithium ion battery can be obviously improved, and the effect of coating the polymer layer containing the carbon nano tube is better than that of independently coating a polymer or a negative active material of the carbon nano tube.
2. Negative active materials of examples 11 to 13 and comparative example 4 were prepared as follows:
(1) respectively carrying out mechanical dry mixing and ball milling mixing on silicon dioxide and metal silicon powder in a molar ratio of about 1:1 to obtain a mixed material;
(2) at Ar2Under an atmosphere of about 10 deg.C-3-10-1Heating the mixed material at a temperature in the range of about 1200 ℃ and 1600 ℃ for about 5-30 hours under the kPa pressure range to obtain a gas;
(3) condensing the gas obtained to obtain a solid;
(4) crushing and screening the solid; and
(5) heat treating said solid at a temperature in the range of about 400-1800 ℃ for about 0.5-15 hours under a nitrogen atmosphere, cooling said heat treated solid and subjecting it to a classification treatment;
(6) coating the solid obtained in the step (5) with a polymer layer containing a carbon material, specifically referring to the step of preparing the negative electrode active material having the polymer layer on the surface.
Specific process parameters in steps (1) - (5) are shown in table 2-1.
TABLE 2-1
Figure GDA0002926826100000182
Tables 2 to 2 show the compositions of the anode active materials in examples 11 to 13 and comparative example 4.
Tables 2 to 2
Figure GDA0002926826100000183
Figure GDA0002926826100000191
Tables 2 to 3 show the performance test results of the lithium ion batteries prepared from the negative active materials in examples 11 to 13 and comparative example 4.
Tables 2 to 3
Figure GDA0002926826100000192
As can be seen from the test results of examples 11 to 13 and comparative example 4, in the case where the polymer clad layer is also present, the composition of the present invention satisfies 0<I2/I1The cycle performance, the anti-expansion performance and the rate capability of the lithium ion battery prepared by the negative active material less than or equal to 1 are superior to those of the lithium ion battery prepared by the negative active material less than or equal to 1<I2/I1The cycle performance and rate capability of the lithium ion battery prepared by the negative active material.
3. Negative active materials of examples 14 to 16 and comparative examples 5 to 6 were prepared by the following methods
Negative active materials of examples 14 to 16 and comparative examples 5 to 6 were obtained by subjecting the negative active material of example 12 to a sieving and classifying treatment.
Table 3-1 shows the compositions of the anode active materials of examples 14-16 and comparative examples 5 and 6.
TABLE 3-1
Figure GDA0002926826100000193
Table 3-2 shows the performance test results of the lithium ion batteries prepared from the negative active materials of examples 14-15 and comparative examples 5 and 6.
TABLE 3-2
Figure GDA0002926826100000194
Figure GDA0002926826100000201
As can be seen from the test results of examples 14 to 16 and comparative examples 5 and 6, when the polymer clad layer is also present and the silicon oxide satisfies 0<I2/I1Under the condition of less than or equal to 1, the cycle performance and rate capability of the lithium ion battery prepared by the negative active material satisfying that Dn10/Dv50 is less than or equal to 0.6 is better than those of the lithium ion battery prepared by Dn10/Dv50<0.25 or 0.6<The cycle performance and rate capability of the lithium ion battery prepared by the negative active material of Dn10/Dv 50.
4. Preparation of MeO with intermediate oxideyNegative active material of layer
Negative active materials of examples 17 to 19 were prepared by the following method:
the preparation methods of the anode active materials of examples 17 to 19 were similar to the preparation method of the anode active material of example 16, except that the preparation methods of examples 17 to 19 were performed on silicon oxide SiOxBefore coating the polymer layer, metal oxide MeO is firstly carried outyCoating of layers, in which the metal oxide MeOyThe step of coating the layer comprises:
(1) silicon oxide SiOxCarbon precursor and oxide precursor MeTnAdding to about 150mL of ethanol and about 1.47mL of deionized water, and stirring for about 4 hours until a homogeneous suspension is formed;
(2) spray drying (inlet temperature about 220 ℃, outlet temperature about 110 ℃) the suspension to obtain a powder; and
(3) sintering the powder at about 250 ℃ and 1000 ℃ for about 0.5-24h to obtain the powder with the oxide MeO on the surfaceySilicon compound SiO of the layerxAnd (3) granules.
Wherein Table 4-1 shows the coated Metal oxides MeO of the negative electrode active materials of examples 17-19yThe specific process conditions of the layer.
TABLE 4-1
Figure GDA0002926826100000202
Table 4-2 shows the compositions of the anode active materials of examples 17-19.
TABLE 4-2
Figure GDA0002926826100000211
Tables 4 to 3 show the performance test results of the lithium ion batteries prepared from the negative active materials of examples 17 to 19.
Tables 4 to 3
Figure GDA0002926826100000212
From the test results of examples 16 to 19, it can be seen that in the presence of the polymer coating layer as well and silicon oxide satisfying 0<I2/I1Under the conditions that the cycling performance and the rate capability of the lithium ion battery prepared by the negative active material with the metal oxide layer between the silicon oxide layer and the polymer layer are less than or equal to 1 and the Dn10/Dv50 is less than or equal to 0.6, the cycling performance and the rate capability of the lithium ion battery prepared by the negative active material without the metal oxide layer are superior to those of the lithium ion battery prepared by the negative active material without the metal oxide layer.
Reference throughout this specification to "some embodiments," "one embodiment," "another example," "an example," "a specific example," or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. Thus, throughout the specification, descriptions appear, for example: "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," "in a particular example," or "by example," which do not necessarily refer to the same embodiment or example in this application. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
Although illustrative embodiments have been illustrated and described, it will be appreciated by those skilled in the art that the above embodiments are not to be construed as limiting the application and that changes, substitutions and alterations can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims (17)

1. An anode material comprising silicon-containing particles comprising a silicon composite matrix, an oxide MeOyA layer and a polymer layer, the polymer layer encasing at least a portion of the silicon composite substrate, and the polymer layer comprising a carbon material;
the oxide MeOyA layer between the silicon composite substrate and the polymer layer; wherein the oxide MeOyA layer comprising a carbon material; wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co or Zr, wherein y is 0.5-3; and is
The weight percentage of the Me element is 0.001 wt% to 0.9 wt% based on the total weight of the anode material.
2. The anode material of claim 1, wherein the silicon composite matrix comprises SiOxAnd x is more than or equal to 0.6 and less than or equal to 1.5.
3. The anode material of claim 1, wherein the silicon composite matrix comprises nano-Si grains, SiO2Or any combination thereof.
4. The anode material of claim 3, wherein the nano-Si grains are less than 100nm in size.
5. The negative electrode material of claim 1, wherein the polymer layer comprises polyvinylidene fluoride and derivatives thereof, carboxymethyl cellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, styrene-butadiene rubber, polyacrylamide, polyimide, polyamideimide, or any combination thereof.
6. The anode material of claim 1, wherein the carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
7. The anode material of claim 1, wherein the weight percentage of the polymer layer is 0.05-15 wt% based on the total weight of the anode material.
8. The anode material according to claim 1, wherein the polymer layer has a thickness of 1nm to 200 nm.
9. The negative electrode material of claim 1, having a maximum intensity value, I, in an X-ray diffraction pattern, 2 Θ, falling within the range of 27.5 ° -29.0 °2The highest intensity value in the range of 20.5-22.0 is I1Wherein 0 is<I2/I1≤1。
10. The anode material of claim 9, wherein D of the silicon-containing particlesV50 is in the range of 2.5 to 20 μm and the particle size distribution of the silicon-containing particles satisfies: dn10/Dv50 is more than or equal to 0.25 and less than or equal to 0.6.
11. The anode material of claim 1, wherein the oxide MeOyThe thickness of the layer is 1nm-800 nm.
12. The negative electrode material according to claim 1, having a specific surface area of 1 to 50m2/g。
13. A method of making the anode material of any one of claims 1-12, the method comprising:
mixing SiOxDispersing the powder, the carbon material and the polymer in a solvent at a high speed for 1-20h to obtain a suspension; and
removing the solvent from the suspension, wherein
0.5<x<1.5。
14. A negative electrode comprising the negative electrode material of any one of claims 1 to 12.
15. An electrochemical device comprising the anode of claim 14.
16. The electrochemical device of claim 15, which is a lithium ion battery.
17. An electronic device comprising the electrochemical device of claim 16.
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